The treatment of pigmented nevi can generally be divided into surgical and non-surgical treatments. Surgical treatment is the most thorough and safer, but it is more expensive and relatively troublesome to operate. For small pigmented nevi that can be clearly benign, it is generally unnecessary. Non-surgical treatment mainly includes drugs, freezing, electrocautery, laser, etc. Among them, laser treatment has the most affirmative effect and can basically eliminate the rest of non-surgical treatment methods, which are most widely used in clinical practice. But which moles can be treated by laser? The following cases are generally considered. 1. Nature: Only if it is clear that the mole is benign, laser can be used to remove it. If the benign or malignant nature of the mole is not clear, it is recommended to take surgery and send the cut down mole for pathological examination after the surgery. The National Cancer Institute has proposed the “ABCD” method to distinguish melanoma from common moles, which represents four symbols, namely asymmetry, edge, color, and the first letter of the English word of diameter. (1) Asymmetry: The two halves of a malignant melanoma are asymmetrical, while the two halves of a common nevus are symmetrical. (2) Margin: The margin of malignant melanoma is untidy and changes into jagged shape, while the margin of common nevus is smooth and clearly demarcated from the surrounding skin. In addition, the surface of malignant melanoma is rough with scaly or flaky desquamation, and sometimes there is oozing or bleeding, and the lesion is higher than the skin. (3) Color: Malignant melanoma will be mixed with pink, white and blue-black on the basis of tan or brown. Among them, blue is the most ominous, and white suggests that the tumor has degenerated on its own. Nodular malignant melanoma is always blue-black or gray, while ordinary moles are usually tan, brown or black. (4) Diameter: Malignant melanoma is larger than 5 mm in diameter, while common nevus is usually smaller than 5 mm in diameter. If a certain pigmented mole shows any of the above changes, it should be a cause for concern and, if necessary, be seen in a hospital. Besides, if a pigmented nevus suddenly itches, pains, redness, surface unevenness, ulceration, bleeding, satellite “small nevus” around it or regional lymph node enlargement, this is a sign of malignant pigmented nevus, which cannot be treated by laser, and must be removed surgically and examined after surgery. 2.Size: moles with diameter <5mm can be treated by laser and the scars are not obvious, while moles with diameter >5mm are generally considered to be surgically excised and cosmetically stitched. However, some exophytic intradermal moles with diameter >5mm can be treated by laser if the growth site is not suitable for surgery, which can also achieve good cosmetic results. 3. Site: Moles on the palms of hands, soles of feet, under finger (toe) nails, mouth and lips and external genitalia have the possibility of malignant transformation and are generally removed by surgery, which is more thorough. Treatment with laser is not absolutely contraindicated, but must be used to try to ensure a clean removal, the corresponding width and depth should be increased, as for the aesthetic requirements is not the first consideration.